Various different ways of folding sheet material have been developed in order to allow sheets containing relatively large amounts of information to be reduced in size to manageable dimensions.
For example, European patent application number EP-A-0 288 472 discloses a folded sheet comprising a first and second set of concertina folds, which sets are transverse to one another. The arrangement of folds allows the sheet to be easily folded and unfolded by having stiff portions at diagonally opposite corner sections of the sheet.
Whilst folded sheets allow a large amount of information to be stored on an article of relatively small size, the method of manufacturing the folded sheets is complicated. In order to provide the sheet with the required folds complex folding apparatus is generally required.
The complex folding apparatus is a deterrent for small-scale manufacturers and individuals wishing to produce such folded sheets.
It is an aim of preferred embodiments of the present invention to provide a sheet material for producing folded sheets that overcomes at least one of the disadvantages of the prior art folded sheets.
It is a further aim of preferred embodiments of the present invention to provide apparatus and methods for producing foldable sheets.